AGRICULTURAL CHEMISTRY 



A. E. Vixsox, C. N. Catlix, S. W. Griffin 



A report of the work of the Department of Agricultural Chem- 

 istry for the first six months of the period covered by the Thirty- 

 first Annual Report was made in the Thirtieth Annual Report. 

 Consequently the present report covers the six months ended 

 June 30, 1920. 



ADAMS FUND AVORK 



Details in the technique of measuring the swelling coefficient 

 of dry soils when wetted have been given further study and 

 several minor improvements effected. The method is now ready 

 for publication. 



The set of pot cultures with wheat in black alkaline soil, 

 previously reported as under way, has been completed. It seems 

 to show the point of tolerance for wheat at something over .2 

 percent of sodium carbonate in the type of soil used and under 

 the conditions of the experiment as described in the Thirtieth An- 

 nual Report. An interesting result of this experiment was that 

 healthier looking plants were obtained in pots containing .1 to 

 .15 percent of sodium carbonate than in those containing small 

 amounts of alkali. The soils with lower percentage of sodium car- 

 bonate were prepared by blending leached black alkaline soil of 

 the same texture as the other soils of the series with unleached 

 soil. The grain yields, however, were highest in the .05 percent 

 sodium carbonate soils. The heaviest grain yields were obtained 

 in soils containing .2 percent of sodium carbonate with sufficient 

 gypsum added to neutralize exactly the sodium carl)onate. Larger 

 amounts of gypsum did not increase the yield, but one-half and 

 one-quarter enough gypsum to neutralize the sodium carbonate 

 gave some increase over the untreated check. Other reagents 

 were used to neutralize the sodium carbonate, but no definite re- 

 sults were obtained. It was apparent that the series throughout 

 contained too few duplicates to give positive conclusions without 

 several repetitions of the experiment. Consequently the facilities 

 for culture work are now being increased to 240 pots. 



